The haploid human genome consists of ~______ nucleotide pairs.
3.2 billion
Define: chromatin
unpackaged DNA material (unwound chromosome)
Chromatin condenses in Mitosis
Define gene;
a gene is a sequence of DNA that codes for one polypeptide or one set of closely related polypeptides (via alternative splicing), or a structural RNA, or a regulatory RNA.
Human cells have ~ _____ genes
~25,000 genes
only ~___% of DNA codes for proteins.
~1.5%
all noncoding DNA is termed _____ ___
"junk DNA"
a Simple sequence repeat is a _____
short nucleotide sequences (>14 NP's) that are repeated again and again for long stretches.
Mitosis is ~____hr in many mammalian cells
1hr
2 groups of protein that package DNA;
1) Histones
2) nonhistones
Histones package DNA into ________
nucleosomes
A nucleosome consists of;
1) a nucleosome core particle
2) Linker DNA - few np's to 80 np's long to the neighbouring nucleosome
The are _ core histones.
8. A pair of H2A, H2B, H3, and H4 histones.
Each core histone has a structural motif (region) called a ____ ____
Histone fold.
Describe the joining process of the core histone octamer.
H3 and H4 form a dimer and then join a similar dimer, forming a tetramer.
H2A and H2B form a dimer as well, join a similar dimer, and form a tetramer as well.
The 2 differnt tetramers join to form the octamer.
What will you find on each end of a histone fold?
One N-terminal tail end - amino end
other end: carbonyl end
What is nucleosome sliding and how is it accomplished?
Nucleosome sliding is the act of pushing the DNA wrapped around the histone core. It is catalyzed through ATP-dependant chromatin remodeling complexes. (uses the energy of ATP hydrolysis).
True/False: H1 is a core histone.
False. H1 is not apart of the nucleosome core particle.
one histone H! binds to each nucleosome
H1 is also a linker histone
2 major types of chromatin include;
Heterochromatin and euchromatin.
Describe heterochromatin.
Condensed
transcriptionally inactive
contains few genes
genes present are to dense to read
Describe euchromatin;
transcriptionally active.
_______ causes modifications to core histone tails.
Histone-modifying enzymes.
Methylation, phosphorylation, acetylation and ubiquitylation
Where can heterochromatin be found?
telomeres, and in/around the centeromere.
______ describes heterochromatin around the centromere.
pericentric heterochromatin.
______ _______ describes heterochromatin within the centromere.
centric heterochromatin.
______ molecules link sister chromatids.
Cohesion molecules.
Centromere Nucleosomes: special proteins called _____ _____ bind to the centromere DNA and form _____ _______.